1. Field of the Invention
The present invention relates generally to video communications systems, and more particularly to a display mode automatic switching system for use with video displays in multi-participant conference systems.
2. Background of the Prior Art
During multi-point videoconferences (those involving three or more conference endpoints), two viewing modes are commonly utilized. In a first mode, called the discussion or continuous presence mode, images of all conference endpoints are displayed simultaneously, each image occupying a separate window. The discussion mode is particularly useful in situations where there is frequent interaction between the conference participants. In a second mode, the image of the endpoint corresponding to the currently speaking participant is displayed full screen at the other endpoints. The full-screen or presentation mode is useful where one conference participant is speaking for an extended period of time.
Some multi-point videoconferences are facilitated through a conference service provider. Conference participants dial into a multi-point control unit provided by the service provider, where the audio, video, and data from the participating endpoints is received, processed, and transmitted to the participating endpoints. In some prior art systems, either a voice-activated video bridge or a continuous presence video bridge is utilized, whereby the chosen viewing mode (presentation mode or discussion mode, respectively) is static throughout the duration of the videoconference. The inherent limitations of a static viewing mode configuration result in a less than optimum conference.
Other prior art systems provide display mode switching capability, wherein switching between the two modes is generally performed by a video processor (typically located at a multi-point control unit) under the manual control of one of the conference participants. However, the need to manually switch between the two modes is distracting and may interrupt the natural flow of communication, again resulting in a diminished conference. In addition, during a multi-party television program production, a production crew typically performs manual switching of display modes during a live interview or discussion.
Therefore, there is a need in the arts to provide a display mode automatic switching system capable of reacting to the interaction of multiple conference participants and managing the video display modes of all conference participants accordingly.
An automatic switching system and method for determining and effecting an optimal video display mode based on the interaction among participants in a conference or discussion is described. Typically, available display modes for a video display device include a discussion mode wherein images from all endpoints are presented simultaneously in separate windows, and a presentation mode wherein images from a single endpoint are presented in a single window. Preferred operating environments of the system and method described herein include multi-point videoconferencing and live television program production.
The system includes a timer which continuously monitors the duration of signals received from each of a number of endpoints. The system further includes a signal switching processor which compares the signal durations to predefined parameters which describe various display mode switching thresholds. The system reacts to the conversational interaction of endpoint participants by automatically transmitting a mode switching command to a video switching processor, thereby effecting the changing of the display mode of all endpoints between a single speaker presentation mode and a multiple speaker discussion mode. The system is automatic in that the switching occurs without any active input from the participants other than their conversational participation.
In preferred embodiments, the automatic switching system reacts to the conversation occurring among the endpoint participants by monitoring the duration of the audio portion of multiplexed audio/video signals received from each of multiple endpoints. In general, a presentation display mode is considered optimal when a speaker from one of the multiple endpoints is the sole, or distinct, speaker. A distinct speaker is defined as a speaker whose speaking duration exceeds a predefined threshold. A discussion display mode is considered optimal when no speakers at any of the endpoints are exceeding a predefined xe2x80x9ccough delayxe2x80x9d threshold, thus eliminating unnecessary and distracting display mode switching. Additionally, the discussion display mode is considered optimal when at least one speaker at more than one endpoint is speaking for a duration exceeding the cough delay.